Electric pipe expander, chuck structure for electric pipe expander, and control circuit for electric pipe expander

ABSTRACT

An electric pipe expander and intelligent control circuit for the electric pipe expander are provided The electric pipe expander includes a pipe expander body and a mandrel sliding cavity disposed on the pipe expander body. A chuck body capable of clamping a pipe to be processed is disposed at an opening end of the mandrel sliding cavity. A mandrel is slidingly connected in the mandrel sliding cavity, an outer side end of the mandrel is provided with an obliquely disposed pipe expanding cone, an inner side end of the mandrel is provided with an elastic body accommodating cavity. Flat keys are disposed on the mandrel, and an elastic body is clamped and disposed between the flat keys and a bottom surface of the elastic body accommodating cavity.

BACKGROUND Technical Field

The present invention relates to a pipe expander, and more particularlyrelates to an electric pipe expander with the advantages of simplestructure, time-saving and labor-saving effects in pipe expandingprocessing and good pipe socket processing quality.

Description of Related Art

In the process of installing or repairing an air conditioner, a pipeexpander is generally needed to perform pipe socket expanding processingon a refrigerant copper pipe. Existing pipe expanders generally includemanual pipe expanders and electric pipe expanders. The manual pipeexpander has a small size and light weight, but wastes time and labor inthe pipe expanding processing, and the pipe socket processing quality isgreatly influenced by artificial factors. The electric pipe expandersaves time and labor in the pipe expanding processing, but isinconvenient to carry and use due to its relatively complex internalmechanical structure and large size. Meanwhile, the two kinds of pipeexpanders generally require to clamp the copper pipe for positioning byusing a clamp with a threaded rotary rod during the pipe expandingprocessing, so that time and labor are wasted during clamping, thepositioning precision of the copper pipe is low, and the pipe socketprocessing quality cannot be guaranteed.

SUMMARY

The present invention mainly provides an electric pipe expander with theadvantages of simple structure, high positioning precision of pipes tobe processed, time-saving and labor-saving effects in pipe expandingprocessing and good pipe socket processing quality, and solves thetechnical problems of complicated structure, time waste and labor wasteduring positioning and clamping of the pipes to be processed, lowpositioning precision, pipe socket processing quality guaranteeingincapability and the like of the electric pipe expander in the priorart.

The present invention mainly solves the above technical problems throughthe following technical solution. An electric pipe expander includes apipe expander body and a mandrel sliding cavity disposed on the pipeexpander body. A chuck body capable of clamping a pipe to be processedis disposed at an opening end of the mandrel sliding cavity, a mandrelis slidably connected in the mandrel sliding cavity, an outer side endof the mandrel is provided with an obliquely disposed pipe expandingcone, an inner side end of the mandrel is provided with an elastic bodyaccommodating cavity, a guide screw rod provided with a transmissionscrew nut is disposed on the pipe expander body opposite to an openingof the elastic body accommodating cavity, the guide screw rod extendsinto the elastic body accommodating cavity, flat keys are disposed onthe mandrel, outer side ends of the flat keys are slidably connected toa worm gear and worm mechanism in an axial direction, inner side ends ofthe flat keys are slidably connected into axial key slots of thetransmission screw nut, and an elastic body is clamped and disposedbetween the flat keys and a bottom surface of the elastic bodyaccommodating cavity. The mandrel configured to push the pipe expandingcone to perform pipe expanding processing is driven through the wormgear and worm mechanism, so that time and labor are saved, and the pipeexpanding processing efficiency is high. The elastic body is disposedbetween the corresponding flat keys in a mandrel accommodating cavityand a bottom surface of the mandrel accommodating cavity, during thepipe expanding processing, a worm gear rotates to drive the flat keys torotate forward, the transmission screw nut synchronously advances alongthe guide screw rod, and the elastic body is axially compressed. Thepipe expanding cone performs pipe expanding processing in a rotarypressing manner, in the processing period, the elastic body deceleratesthe axial moving speed of the mandrel through self deformation, and thesingle cycle axial feeding deformation amount is decreased, so that aperipheral shape of a pipe socket of the pipe to be processed becomesuniform, and the processing quality of the pipe socket is effectivelyguaranteed. On one hand, the guide screw rod achieves a supportpositioning and guide effect on the mandrel, and on the other hand, themandrel can use a plastic material on the premise of ensuring a strengthrequirement, the strength is guaranteed through the transmission screwnut made of a metal material, the manufacturing cost can be reduced, atthe same time, the weight of the whole machine can be reduced, and theuse and carrying are convenient.

Preferably, a cone positioning hole is formed in an end surface of themandrel corresponding to the pipe expanding cone, an included angle isformed between an axial line of the cone positioning hole and an axialline of the mandrel, and the pipe expanding cone is rotationallyconnected into the cone positioning hole through a cone bearing. Thepipe expanding cone is obliquely fixed onto an outer end surface of themandrel to realize the rotary pressing type pipe expanding processing.The pipe expanding cone maintains rotational connection with the mandrelthrough a cone bearing, so that the pipe expanding cone can freelyrotate along a self axial line, so that rolling friction is maintainedbetween the pipe expanding cone and a pipe expanding copper pipe duringthe rotary pressing pipe expanding processing, time and labor are savedin the pipe expanding processing, at the same time, the surface abrasionof the pipe expanding cone is uniform and consistent, the service lifeof the pipe expanding cone is prolonged, and the pipe expandingprocessing quality is indirectly guaranteed.

Preferably, a mandrel bearing is embedded in the pipe expander bodycorresponding to the outer side end of the mandrel, a support ring isdisposed between a middle hole of the mandrel bearing and an outer ringsurface of the mandrel, and an inner end of the support ring extendsinto a middle hole of a worm gear on the worm gear and worm mechanismand is in close fit with the worm gear. The support ring extends intothe middle hole of the worm gear, so that the stable support of themandrel can be realized through a single bearing, the cost is saved, andat the same time, the whole structure is compacter.

Preferably, the elastic body is an annular rubber component, and theguide screw rod extends into a middle hole of the elastic body. Theelastic body made of an annular rubber material is low in cost, and atthe same time, an annular structure provides a storage space for theguide screw rod, so that the thickness of the transmission screw nut canbe reduced.

Preferably, a pipe expanding cavity is formed in the pipe expander bodycorresponding to the chuck body, a clamping end of the chuck bodyextends into the pipe expanding cavity and is clamped and fixed througha clamping connecting rod mechanism, and an outer end surface of thechuck body is in butt joint with a corresponding inner wall surface ofthe pipe expanding cavity. Through the arrangement of the pipe expandingcavity outside an end opening of the mandrel sliding cavity, the chuckbody can be fed into the pipe expanding cavity from the end opening atthe side surface of the chuck body, the chuck body is positioned in acircumferential direction through the clamping connecting rod mechanism,the outer end surface of the chuck body is positioned through the innerwall surface of the pipe expanding cavity, the axial displacement of thechuck body together with the pipe to be processed in the pipe expandingprocessing process is prevented, the positioning of the pipe to beprocessed is precise, and the pipe expanding processing quality issufficiently guaranteed.

More preferably, a connecting rod accommodating cavity is formed in thepipe expander body corresponding to a periphery of the pipe expandingcavity, the clamping connecting rod mechanism is disposed in theconnecting rod accommodating cavity, a press plate corresponding to oneend of the clamping connecting rod mechanism extends into the pipeexpanding cavity, and the other end of the clamping connecting rodmechanism is connected with a linkage wrench extending out of the pipeexpander body. Through the arrangement of the connecting rodaccommodating cavity with the connecting rod mechanism on the pipeexpander body, the press plate at one end of the connecting rodmechanism tightly presses a side wall of the chuck body onto an annularwall surface of the pipe expanding cavity for peripheral fixation, theother end of the connecting rod mechanism is further provided with thelinkage wrench, the linkage wrench extends out of the pipe expanderbody, the linkage wrench is pulled during clamping positioning, theconnecting rod mechanism can drive the press plate to tightly clamp thechuck body, the operation is convenient, and time and labor are saved.At the same time, the linkage wrench can trigger a relevant actionswitch on the system, such as starting or instant stop, and theautomation and intelligence of the pipe expanding processing arerealized.

More preferably, an adjusting screw is screwed and connected onto thepipe expander body, the connecting rod mechanism is driven when theadjusting screw screws in, and the press plate is in butt joint with theside wall of the chuck body in a tightly clamping manner. Through thearrangement of the adjusting screw at the other end of the connectingrod mechanism, when the chuck body is abraded, the adjusting screw canbe screwed into the connecting rod accommodating cavity, the adjustingscrew drives the connecting rod mechanism to move, and then, the pressplate on the connecting rod mechanism tightly presses the chuck body sothat the chuck body is precisely and tightly clamped between the pressplate and an inner wall surface of the pipe expanding cavity. Thepressure for locking the chuck body can be freely adjusted, at the sametime, a mechanism assembly error and an error caused by use abrasion arecompensated, the structure is simple, the service life of the pipeexpander is prolonged, and the pipe expanding processing quality isguaranteed.

More preferably, an end portion of the press plate corresponding to thechuck body horizontally and outwards extends to form a trapezoidal presshead, a trapezoidal clamping opening is formed in a side wall of thechuck body corresponding to the trapezoidal press head, and when thepress plate tightly clamps the chuck body, the press plate is in buttjoint with a bottom surface of the trapezoidal clamping opening througha bottom edge of the trapezoidal press head, and is in butt joint with abevel edge at a lower part of the trapezoidal clamping opening through abevel edge at a lower part of the trapezoidal press head. The pressplate tightly clamps after the trapezoidal press head is fit with thecorresponding trapezoidal clamping opening on the chuck body,additionally, the bevel edge at the lower part of the trapezoidal presshead is in butt joint with the bevel edge at the lower part of thetrapezoidal clamping opening, the lower bevel edges of the trapezoidalpress head and the trapezoidal clamping opening outwards and downwardsextend, so that clamping force can be formed in a horizontal directionand a vertical direction when the trapezoidal press head and thetrapezoidal clamping opening are tightly pressed in a fit manner, andthe chuck body is enabled to be firmly fixed in the pipe expandingcavity. At the same time, due to the trapezoidal structure, a press-inend of the trapezoidal press head is in plane transition, on one hand,the trapezoidal press head can conveniently slide into the trapezoidalclamping opening, on the other hand, sharp corner scratching injury isprevented, and the use safety is improved.

More preferably, a horizontal position limiting post is disposed on thepipe expanding cavity opposite to the press plate on the clampingconnecting rod mechanism, and a mutually matched horizontal throughgroove is formed in a side wall of the chuck body corresponding to thehorizontal position limiting post. The other side of the chuck body ispositioned through the mutually matched horizontal through groove andhorizontal position limiting post, and the positioning accuracy of thechuck body is guaranteed.

More preferably, a pressing end of the clamping connecting rod mechanismis in butt joint with a side wall of a rotating shaft far away from thechuck body, and maintains sliding connection with a side wall surface ofthe chuck body. The pressing position of the connecting rod mechanism isdownwards moved to the end portion far away from the rotating shaft, inthe pressing process, the pressing end of the connecting rod mechanismmaintains sliding connection with the side wall surface of the chuckbody, so that the pressing force from the connecting rod mechanismtotally acts on a chuck, the pipe to be processed is firmly clamped andfixed into the positioning hole of the chuck body, the pressing forcehas no component force in a vertical direction, and the use efficiencyof the pressing force is improved. At the same time, a stress point ofthe chuck body is far away from the rotating shaft, a lever force arm islonger, the clamping force of the pipe to be processed is increased, andthe clamping effect is enhanced. Therefore, the pipe expandingprocessing quality is better guaranteed.

Preferably, a plastic casing covers an outside of the pipe expanderbody, the plastic casing extends outwards to form a motor accommodatingcavity, a motor is disposed in the motor accommodating cavity, an outputshaft end of the motor is connected with the worm gear and wormmechanism, and the other end of the motor is electrically connected witha rechargeable battery. The whole machine uses the plastic casing, sothat an internal circuit is completely isolated from an externalenvironment, and the safety is high. At the same time, the plastic hasgood heat insulation performance, and a hot-to-handle risk cannot occurafter long-time continuous use.

More preferably, the rechargeable battery includes a battery packdisposed in a battery pack accommodating cavity on the pipe expanderbody. An ID detection port, a voltage detection port and a temperaturedetection port are disposed on a protective case of the battery pack,and the ID detection port, the voltage detection port and thetemperature detection port are all connected to a battery cell in theprotective case through a battery circuit board. The ID detection port,the voltage detection port and the temperature detection port aredisposed on the rechargeable battery, through the ID detection port, theinfluence on the use performance of the electric pipe expander due touse of batteries of other brands in the electric pipe expander isavoided, and the use safety of the electric pipe expander is guaranteed.Through the voltage detection port, the charging and discharging voltageof the battery can be detected, and charging and discharging protectionis further achieved. Through the temperature detection port, the batterytemperature can be monitored in real time, safety accidents caused bybattery overheat and the like are prevented. The whole structure issimple, the safety and reliability are high, and the service lives ofthe battery and the electric pipe expander are guaranteed.

Preferably, the chuck body includes a left clamp body and a right clampbody, middle portions of the left clamp body and the right clamp bodyare rotationally connected onto a rotating shaft, the corresponding leftclamp body and right clamp body at one side of the rotating shaft form aclamping end for clamping the pipe to be processed, and thecorresponding left clamp body and right clamp body at the other side ofthe rotating shaft respectively form force application handles. The pipeto be processed is clamped and fixed through the chuck body of ascissor-like structure, the positioning is reliable, and the mountingand dismounting are convenient.

More preferably, a positioning bulge and a positioning groove matchedwith each other are disposed between matching surfaces of the left clampbody and the right clamp body. Through the arrangement of thepositioning bulge and the positioning groove which are matched with eachother between the matching surfaces at the outer sides of the left clampbody and the right clamp body, when the pipe to be processed is in aclamped state, the positioning bulge is inserted into the positioninggroove for positioning, thus preventing the occurrence of axialstaggering of the left and right clamp bodies and preventing theinfluence on the pipe expanding processing precision.

Preferably, an end surface baffle plate is rotationally connected ontoan end surface of the chuck body in adjacent to the pipe expanding cone,and an end surface of the pipe to be processed is in butt joint with acorresponding outer side surface of an inner side end of the end surfacebaffle plate. Through the arrangement of the end surface baffle plate onthe inner side end surface of the chuck body, the axial position of thepipe to be processed can be precisely positioned, so as to guarantee thepipe expanding processing quality.

Preferably, the end surface baffle plate is movably sleeved on a pinsleeve, the pin sleeve is screwed, connected and fixed to an end portionof a rotating shaft of the chuck body through a threaded connectingcomponent in close fit, an outer ring surface of the pin sleeve outwardsextends along an outer end surface of the end surface baffle plate toform an end surface baffle ring, and the end surface baffle plate ismovably clamped between the end surface baffle ring and an end surfaceof the chuck body. The end portion of the rotating shaft is coaxiallyscrewed, connected and fixed with the pin sleeve with the end surfacebaffle ring through the threaded connecting component, the end surfacebaffle plate is sleeved on the pin shaft so that the end surface baffleplate is clamped between the end surface baffle ring and the end surfaceof the chuck body. During installation, a gap of the end surface baffleplate can be firstly adjusted by rotating the pin sleeve, and then, thethreaded connecting component is screwed and fixed onto the pin sleeveso as to be in close fit with the pin sleeve to avoid the increase ofthe gap of the end surface baffle plate caused by the looseness of thepin sleeve generated in the use process, the structure is simple, thegap of the end surface baffle plate can be conveniently adjusted andprecisely controlled, and the pipe expanding processing quality isguaranteed.

More preferably, the pin sleeve extends into an installing hole of thechuck body, and a chuck body reset torsional spring is sleeved outsidethe corresponding pin sleeve in the installing hole. The chuck bodyreset torsional spring is configured to reset the left and right chuckbodies after the pipe to be processed is unclamped.

An intelligent control circuit for an electric pipe expander includes asingle chip microcomputer unit, a mandrel stroke detection unit, awrench position detection unit, a motor driving unit and a power supplyunit for providing work voltage for the whole intelligent controlcircuit for the electric pipe expander. The mandrel stroke detectionunit, the wrench position detection unit and the motor driving unit arerespectively connected to the single chip microcomputer unit. Themandrel stroke detection unit detects whether a pipe expanding headadvances to exceed an allowable range or not (if YES, damage of the pipeexpander may be caused), and also detects whether the pipe expendinghead retreats to an initial position before starting or not. The wrenchposition detection unit detects whether a wrench on the pipe expander isin a closed locked state or an open state, detection signals arerespectively sent to the single chip microcomputer unit, the single chipmicrocomputer unit gives a corresponding control signal to the motordriving unit according to the detected conditions to control the motorto positively rotate, reversely rotate or stop rotating, and theautomatic control of the pipe expanding head is achieved. According tothe technical solution, the pipe expanding process is controlled in thewhole process, whether the pipe expansion is completed or not or whetherthe retreating is in place or not after the pipe expansion and therotation of the motor are automatically completed through the controlcircuit, the influence on the pipe expansion caused by artificialfactors is avoided, the pipe expansion reliability is improved, the timeand labor are saved, and the whole-process automatic operation isrealized.

Preferably, the mandrel stroke detection unit includes a pipe expandinghead advancing position limiting switch J3 and a pipe expanding headretreating position detection switch J5. One pin of the pipe expandinghead advancing position limiting switch J3 is grounded, and the otherpin of the pipe expanding head advancing position limiting switch J3 isconnected to the single chip microcomputer unit through a resistor R23.One pin of the pipe expanding head retreating position detection switchJ5 is grounded, and the other pin of the pipe expanding head retreatingposition detection switch J5 is connected to the single chipmicrocomputer unit through a resistor R25. When the motor positivelyrotates, and the pipe expanding head advances for working, the pipeexpanding head retreating position detection switch J5 is in an offstate. After the work of the pipe expanding head is completed, the motorreversely rotates, the pipe expanding head retreats back to the initialposition before starting, and the pipe expanding head retreatingposition detection switch J5 is in an on state. At this moment, a singlechip microcomputer gives out a signal to control the motor to stopworking. That is, the single chip microcomputer determines whether thepipe expanding head returns to the initial position or not by detectingwhether the pipe expanding head retreating position detection switch J5is in in on state or not. If the pipe expanding head retreating positiondetection switch J5 is in the on state, it shows that the pipe expendinghead has returned to the initial position, and the motor stops rotating.The pipe expanding head advancing position limiting switch J3 is in anormally off state, when the pipe expanding head advances to exceed theallowable range (damage of the pipe expander may be caused), the pipeexpanding head advancing position limiting switch J3 is switched on, andat this moment, the single chip microcomputer immediately gives out asignal to control the motor to reversely rotate, so that the pipeexpanding head retreats to return to the initial position beforestarting. The effect is to avoid the occurrence of a machine damagephenomenon caused when an operator starts the pipe expander by mistakebefore the chuck is installed.

Preferably, the wrench position detection unit includes a wrenchposition detection switch J4, one pin of the wrench position detectionswitch J4 is grounded, and the other pin of the wrench positiondetection switch J4 is connected to the single chip microcomputer unitthrough a resistor R24. When the wrench is in a closed locking position,the wrench position detection switch J4 is switched on, the pipeexpander can be started to work. When the mandrel motor positivelyrotates, if the wrench is opened, then the wrench position detectionswitch J4 is switched off, the single chip microcomputer can control themotor to immediately rotate reversely, and the pipe expanding headretreats to the initial position before starting. The starting bymistake under the wrench opening condition is avoided.

Preferably, the intelligent control circuit for the electric pipeexpander includes a motor current acquisition unit. The motor currentacquisition unit includes an operational amplifier U1B, an invertedphase input end and an in-phase input end of the operational amplifierU1B are respectively connected to two ends of a current samplingresistor disposed in the motor driving unit through a resistor R13 and aresistor R18, the inverted phase input end of the operational amplifierU1B is connected to an output end of the operational amplifier U1Bthrough a resistor R8, the in-phase input end of the operationalamplifier U1B is grounded through a capacitor C6 and is connected to avoltage 3.3V_A through a resistor R20, the output end of the operationalamplifier U1B is grounded through a series circuit of a resistor R15 anda capacitor C5, and a connecting point of the resistor R15 and thecapacitor C5 is connected to the single chip microcomputer unit. Themotor current acquisition unit detects work current of the motor, andtransmits the result to the single chip microcomputer. When a set valueis exceeded, the single chip microcomputer can control the motor to stoprotating, and the machine is prevented from burnt damage.

Preferably, the intelligent control circuit for the electric pipeexpander includes a motor short circuit protection unit. The motor shortcircuit protection unit includes an operational amplifier U1A, aninverted phase input end of the operational amplifier U1A is connectedto the motor driving unit through a resistor R10, an in-phase input endof the operational amplifier U1A is connected to a voltage 3.3V_Athrough a resistor R16 and is grounded through a resistor R19, one pathof an output end of the operational amplifier U1A is connected to avoltage 3.3V_A through a resistor R11, and the other path of the outputend of the operational amplifier U1A is connected to the single chipmicrocomputer unit through a resistor R14. The motor short circuitprotection unit detects whether the motor generates a short circuit ornot, once the short circuit is detected, the single chip microcomputerimmediately controls the motor to stop rotating, and a protection effectis achieved on the motor and the pipe expander.

Preferably, electric power of the power supply unit is supplied by abattery, the intelligent control circuit for the electric pipe expanderincludes a battery voltage detection unit and a battery level indicatingunit. The battery voltage detection unit includes a resistor R9 and aresistor R17, one end of the resistor R9 is connected to a positiveelectrode of the battery, the other end of the resistor R9 is groundedthrough the resistor R17, a capacitor C4 is connected in parallel ontothe resistor R17, and a connecting point of the resistor R9 and theresistor R17 is connected to the single chip microcomputer unit througha resistor R12. The battery level indicating unit includes lightemitting diodes D11 to D14 arranged into a row, negative electrodes ofthe light emitting diodes D11 to D14 are all grounded, and positiveelectrodes of the light emitting diodes D11 to D14 are respectivelyconnected to the single chip microcomputer unit through a resistor R1, aresistor R2, a resistor R5 and a resistor R6. The battery voltagedetection unit detects the battery level, and transmits the result tothe single chip microcomputer, the single chip microcomputer outputs asignal to control the on-off state of battery level indicating lampsconsisting of the four light emitting diodes, the battery level isindicated by the number of on/off light emitting diodes of the fourlight emitting diodes arranged into a row, so that the battery can betimely replaced, and the normal work of the pipe expander is guaranteed.

Preferably, the intelligent control circuit for the electric pipeexpander includes a battery temperature detection unit. The batterytemperature detection unit includes a thermistor disposed on thebattery, one end of the thermistor is grounded, the other end of thethermistor is connected to a voltage 3.3V_D through a resistor R21, anda connecting point of the thermistor and the resistor R21 is connectedto the single chip microcomputer unit through a resistor R22. Thebattery temperature detection unit detects the temperature of a batterypack, and transmits the result to the single chip microcomputer, whenthe temperature exceeds a set value, the single chip microcomputercontrols the motor to stop rotating, and an overtemperature protectioneffect is achieved.

Preferably, the power supply unit includes a power supply conversioncircuit and a main power supply switch circuit, the main power supplyswitch circuit includes an illumination switch S1 and a wake-up switchJ6, one end of the illumination switch S1 is grounded, the other end ofthe illumination switch S1 is connected to negative electrodes of adiode D1 and a diode D3, a positive electrode of the diode D1 isconnected to a voltage 3.3V_D through a resistor R28 and is connected tothe single chip microcomputer unit, a positive electrode of the diode D3is connected to a positive electrode of a diode D4, a negative electrodeof the diode D4 is connected to one end of the wake-up switch J6 and isconnected to a negative electrode of a diode D2, the other end of thewake-up switch J6 is grounded, a positive electrode of the diode D2 isconnected to a voltage 3.3V_D through a resistor R29 and is connected tothe single chip microcomputer unit, the positive electrode of the diodeD3 is connected to a collecting electrode of a triode Q2 through amagnetic bead FB3, an emitting electrode of the triode Q2 is grounded, abase electrode of the triode Q2 is connected to the single chipmicrocomputer unit through a resistor R31 and is grounded through aresistor R32, the collecting electrode of the triode Q2 is connected toa base electrode of a triode Q1 through a resistor R30, a resistor R27is connected between the base electrode of the triode Q1 and an emittingelectrode of the triode Q1, the emitting electrode of the triode Q1 isconnected to a voltage VCC, and a collecting electrode of the triode Q1is connected to a voltage 7.2 V. An illumination lamp is disposed on thepipe expander, a positive electrode of the illumination lamp isconnected to the single chip microcomputer unit through a resistor R3,and a negative electrode of the illumination lamp is grounded. Theillumination switch S1 controls the on-off state of the illuminationlamp connected onto an interface J2. The illumination lamp is configuredto illuminate a peripheral environment when the pipe expander is usedand to enable an operator to be able to do pipe expanding work in a darkenvironment. The wake-up switch J6 is configured to wake up the wholecontrol circuit, and the pipe expander can work only after the controlcircuit is woke up.

Preferably, the intelligent control circuit for the electric pipeexpander includes a light emitting diode D15 as a motor work indicatinglamp. A positive electrode of the light emitting diode D15 is connectedto the single chip microcomputer unit through a resistor R7, and anegative electrode of the light emitting diode D15 is grounded. Themotor work indicating lamp indicates the operation of the motor. Theillumination lamp is on when the motor rotates, and the illuminationlamp is off when the motor stops rotating.

Therefore, the electric pipe expander of the present invention has thefollowing advantages. A worm gear and worm transmission structure with asimple structure is used. Compared with those of an existing electricpipe expander, the whole machine length is reduced by about 25%, and theweight is reduced by about 34%. A chip is used for controlling the pipeexpanding process in the whole process. The automatic pipe expansion isrealized after one-key starting. The automatic resetting is realizedafter the pipe expansion is completed. The time and the labor are saved,and the operation is convenient. The pipe to be processed is installedand clamped by the clamping connecting rod mechanism, the time and thelabor are saved during the installation and clamping, and convenienceand high speed are realized. In the processing period, the elastic bodydecelerates the axial moving speed of the mandrel through selfdeformation, and the single cycle axial feeding deformation amount isdecreased, so that a peripheral shape of a pipe socket becomes uniform,and the processing quality of the pipe socket is effectively guaranteed.A mechanism assembly error and an error caused by use abrasion arecompensated by the adjusting screw on the clamping connecting rodmechanism, so that the service life of the pipe expander is prolonged,and the pipe expanding processing quality is guaranteed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic local structure diagram of an electric pipeexpander of the present invention.

FIG. 2 is a schematic structure diagram of the present invention after abaffle plate is dismounted.

FIG. 3 is a schematic structure diagram of the present invention.

FIG. 4 is a schematic local structure diagram of the present inventionin a first implementation.

FIG. 5 is a schematic local structure diagram of the present invention.

FIG. 6 is a schematic structure diagram of a chuck body of the presentinvention.

FIG. 7 is a schematic structure diagram of another chuck body of thepresent invention.

FIG. 8 is a schematic structure diagram of a rechargeable battery of thepresent invention.

FIG. 9 is a schematic local structure diagram of the present inventionin a second implementation.

FIG. 10 is a partial cross-sectional view as shown in FIG. 9.

FIG. 11 is an exploded view of a chuck body of the present invention.

FIG. 12 is a cross-sectional view of FIG. 11.

FIG. 13 is a block diagram of a circuit connection structure of thepresent invention.

FIG. 14 is a schematic circuit diagram of a power conversion unit of thepresent invention.

FIG. 15 is a schematic circuit diagram of a main power supply switchcircuit of the present invention.

FIG. 16 is a schematic circuit diagram of a single chip microcomputerunit, a mandrel stroke detection unit, a wrench position detection unit,a battery voltage detection unit, a battery temperature detection unit,a battery level indicating unit, a motor work indicating lamp and a pipeexpander external illumination lamp of the present invention.

FIG. 17 is a schematic circuit diagram of a motor current acquisitionunit of the present invention.

FIG. 18 is a schematic circuit diagram of a motor short circuitprotection unit of the present invention.

In the figures, 1 denotes pipe expander body, 2 denotes mandrel slidingcavity, 3 denotes pipe to be processed, 4 denotes chuck body, 41 denotesleft clamp body, 42 denotes right clamp body, 43 denotes rotating shaft,44 denotes force application handle, 5 denotes mandrel, 51 denotes conepositioning hole, 52 denotes cone bearing, 6 denotes pipe expandingcone, 7 denotes elastic body accommodating cavity, 8 denotes guide screwrod, 9 denotes transmission screw nut, 10 denotes flat key, 11 denotesaxial key slot, 12 denotes elastic body, 13 denotes pipe expandingcavity, 14 denotes mandrel bearing, 15 denotes support ring, 16 denotesworm gear, 17 denotes connecting rod accommodating cavity, 18 denotesclamping connecting rod mechanism, 181 denotes press plate, 182 denoteslinkage wrench, 183 denotes first fixing pin, 184 denotes connectingplate, 185 denotes horizontal sliding plate, 186 denotes horizontalslotted hole, 187 denotes second fixing pin, 188 denotes trapezoidalpress head, 19 denotes adjusting screw, 20 denotes trapezoidal clampingopening, 21 denotes plastic casing, 22 denotes motor accommodatingcavity, 23 denotes motor, 24 denotes rechargeable battery, 25 denotesillumination lamp, 26 denotes baffle plate, 261 denotes pipe guide-innotch, 27 denotes worm, 28 denotes horizontal position limiting post, 29denotes horizontal through groove, 102 denotes battery packaccommodating cavity, 103 denotes battery pack, 1031 denotes protectivecase, 1032 denotes ID detection port, 1033 denotes voltage detectionport, 1034 denotes temperature detection port, 1035 denotes batterycircuit board, 117 denotes positioning bulge, 118 denotes positioninggroove, 119 denotes end surface baffle plate, 216 denotes sleeve pin,217 denotes threaded connecting component, 2161 denotes end surfacebaffle ring, 218 denotes reset torsional spring, 301 denotes single chipmicrocomputer unit, 302 denotes mandrel stroke detection unit, 303denotes wrench position detection unit, 304 denotes motor driving unit,305 denotes motor current acquisition unit, 306 denotes motor shortcircuit protection unit, 307 denotes battery voltage detection unit, 308denotes battery temperature detection unit, and 309 denotes batterylevel indicating unit.

DESCRIPTION OF THE EMBODIMENTS

The technical solution of the present invention is further specificallydescribed in combination of the following embodiments and theaccompanying drawings.

Embodiment 1

As shown in FIG. 3 and FIG. 5, an electric pipe expander of the presentinvention includes a pipe expander body 1. A plastic casing 21 isdisposed outside the pipe expander body 1 in a covering manner, and theplastic casing 21 extends downwards to form a long-strip-shaped motoraccommodating cavity 22. A rechargeable battery 24, a motor 23 and aworm gear and worm mechanism are sequentially disposed in the motoraccommodating cavity 22 from bottom to top, an output shaft end of themotor 23 is coaxially connected onto a worm 27 of the worm gear and wormmechanism, and the other end of the motor 23 is electrically connectedto the rechargeable battery 24. As shown in FIG. 1, a mandrel slidingcavity 2 is disposed on the pipe expander body 1 corresponding to a wormgear 16 of the worm gear and worm mechanism, the mandrel sliding cavity2 is coaxial with the worm gear 16 and extends into a middle hole of theworm gear 16, a chuck body 4 capable of clamping a pipe to be processed3 is disposed at an opening end of the mandrel sliding cavity 2, amandrel 5 made of a plastic material is slidingly connected in themandrel sliding cavity 2, an outer side end surface of the mandrel 5corresponding to the chuck body 4 is an inclined plane, a conepositioning hole 51 is vertically formed in a middle portion of theinclined plane, an included angle of 8° is formed between an axial lineof the cone positioning hole 51 and an axial line of the mandrel 5, apipe expanding cone 6 is disposed in the cone positioning hole 51, and aconnecting end of the pipe expanding cone 6 is rotationally connected inthe cone positioning hole 51 through a cone bearing 52. A middle portionof an inner side end of the mandrel 5 opposite to the pipe expandingcone 6 is provided with an elastic body accommodating cavity 7, a guidescrew rod 8 is coaxially fixed onto the pipe expander body 1corresponding to an opening end of the elastic body accommodating cavity7, an outer side end of the guide screw rod 8 extends out of the pipeexpander body 1 and is tightly locked through a screw nut, an inner sideend of the guide screw rod 8 extends into a middle hole of the elasticbody accommodating cavity 7, a transmission screw nut 9 made of a metalmaterial is screwed and connected onto the corresponding guide screw rod8 in the middle hole of the elastic body accommodating cavity 7, twoaxial key slots 11 are symmetrically formed in the transmission screwnut 9, and back side ends of the two axial key slots 11 communicate witha rear end surface of the transmission screw nut 9.

Two flat keys 10 are alternately fixed onto the mandrel 5 near the endopening of the elastic body accommodating cavity 7. In order to reducefriction and weight, each of the flat keys 10 is in a cylindrical shape,outer side ends of the flat keys 10 are slidingly connected intocorresponding axial through grooves in the middle hole of the worm gear16 in an axial direction, and inner side ends of the flat keys 10 areslidingly connected into the corresponding axial key slots 11 in thetransmission screw nut 9. An elastic body 12 made of a rubber materialis clamped and disposed between the flat keys 10 and a bottom surface ofthe elastic body accommodating cavity 7. The elastic body 12 is in anannular shape. The inner side end of the guide screw rod 8 can extendinto a middle hole of the elastic body 12. A mandrel bearing 14 iscoaxially embedded and fixed in the pipe expander body 1 correspondingto an outer side end of the mandrel 5, a support ring 15 is clamped anddisposed between a middle hole of the mandrel bearing 14 and an outerring surface of the mandrel 5, and an inner end of the support ring 15extends out of the mandrel bearing 14 and then enters a correspondingannular groove in the middle hole of the worm gear 16. The support ring15 maintains close fit with the annular groove. A pipe expanding cavity13 is formed in the pipe expander body 1 corresponding to the chuck body4, the pipe expanding cavity 13 is defined by a U-shaped baffle plate26, the U-shaped baffle plate 26 is fixed onto the pipe expander body 1with an opening end facing the mandrel 5, and a lower end opening of thebaffle plate 26 faces one end of the motor accommodating cavity 22. Apipe guide-in notch 261 is formed in the middle portion of the bottomsurface corresponding to the upper end opening of the baffle plate 26,the clamping end of the chuck body 4 downwards enters the pipe expandingcavity 13 from the upper end opening of the baffle plate 26, two sidesurfaces of the chuck body 4 entering the pipe expanding cavity 13 areclamped and fixed through a clamping connecting rod mechanism 18, and anouter end surface is parallelly in butt joint with the bottom surface ofthe U-shaped baffle plate 26. As shown in FIG. 2 and FIG. 4, aconnecting rod accommodating cavity 17 is formed in the pipe expanderbody 1 corresponding to the periphery of the pipe expanding cavity 13,the connecting rod accommodating cavity 17 is in an L shape, atransverse edge of the L shape is horizontally positioned under the pipeexpanding cavity 13 and communicates with the left side end of the pipeexpander body 1, and a longitudinal edge of the L shape is upward alongthe right side of the pipe expanding cavity 13 and communicates with thepipe expanding cavity 13. The clamping connecting rod mechanism 18 ispositioned in the connecting rod accommodating cavity 17, the connectingrod mechanism includes a press plate 181 rotationally connected onto aninner wall of the connecting rod accommodating cavity 17 through a firstfixing pin 183, the first fixing pin 183 is positioned in a longitudinaledge cavity near a transverse edge cavity of the connecting rodaccommodating cavity 17, an upper end of the press plate 181 extendsinto the pipe expanding cavity 13, and a lower end of the press plate181 is rotationally connected to one end of a connecting plate 184. Theother end of the connecting plate 184 is rotationally connected to oneend of a horizontal sliding plate 185, the connecting plate 184 and thehorizontal sliding plate 185 are both positioned in a cavitycorresponding to the transverse edge of the connecting rod accommodatingcavity 17, an outer side end of the horizontal sliding plate 185 is neara left end opening of the connecting rod accommodating cavity 17, anadjusting screw 19 is screwed and connected in a left side end opening,and an inner side end of the adjusting screw 19 is in butt joint withthe outer side end of the horizontal sliding plate 185. A second fixingpin 187 is fixed onto the inner wall of the connecting rod accommodatingcavity 17 near the adjusting screw 19, the second fixing pin 187 isparallel to the first fixing pin 183, a horizontal slotted hole 186 isformed in the horizontal sliding plate 185, the horizontal sliding plate185 is glidingly connected onto the second fixing pin 187 through thehorizontal slotted hole 186, the connecting rod mechanism 18 is drivenwhen the adjusting screw 19 is screwed in, and the press plate 181 is inbutt joint with the side wall of the chuck body 4 in a tightly clampingmanner. One end of a linkage wrench 182 is also connected between aconnecting shaft of the connecting plate 184 and the horizontal slidingplate 185 and the second fixing pin 187, the other end of the linkagewrench 182 extends out of the pipe expander body 1 in a manner of beingopposite to the pipe guide-in notch 261, and additionally, an outer sideend of the linkage wrench is near the motor accommodating cavity 22. Theend portion of the press plate 181 corresponding to the chuck body 4horizontally and outwards extends to form an integrally connectedtrapezoidal press head 188. A small bottom surface end of thetrapezoidal press head 188 is pointed to the chuck body 4, an includedangle formed between a lower side bevel edge of the trapezoidal presshead 188 and a big bottom surface is 45°, and a trapezoidal clampingopening 20 is formed in the side wall of the chuck body 4 correspondingto the trapezoidal press head 188. When the press plate 181 tightlyclamps the chuck body 4, the press plate 181 is in butt joint with abottom surface of the trapezoidal clamping opening 20 through a bottomedge of the trapezoidal press head 188, and is in butt joint with abevel edge at the lower part of the trapezoidal clamping opening 20through a bevel edge at the lower part of the trapezoidal press head188, and a gap is formed between a bevel edge at the upper part of thetrapezoidal press head 188 and a bevel edge at the upper part of thetrapezoidal clamping opening 20. A horizontal position limiting post 28is fixed onto an inner wall of the pipe expanding cavity 13 opposite tothe press plate 181, the horizontal position limiting post 28 keepsparallel with the second fixing pin 187 and the first fixing pin 183,and mutually matched horizontal through grooves 29 are formed in theside walls of the chuck body 4 corresponding to the horizontal positionlimiting post 28. In order to prevent the abrasion of the press plate181 and the chuck body 4, the press plate 181 is externally providedwith a plastic protective sleeve, and the plastic protective sleeve isprocessed through injection molding. The chuck body 4 includes a leftclamp body 41 and a right clamp body 42 in symmetrical arrangement, andmiddle portions of the left clamp body 41 and the right clamp body 42are rotationally connected onto a rotating shaft 43. In order to reducethe weight under the condition of ensuring the strength, a high-strengthplastic shell respectively covers each of the left clamp body 41 and theright clamp body 42, semicircular notches for clamping the pipe to beprocessed 3 are respectively formed in the left clamp body 41 and theright clamp body 42 corresponding to the clamping end, the trapezoidalclamping opening 20 is respectively positioned on the outer side wallsof the left clamp body 41 and the right clamp body 42 opposite to thesemicircular notches, the left clamp body 41 and the right clamp body 42opposite to the clamping end respectively form force application handles44, and the force application handles 44 are positioned outside the pipeexpanding cavity 13. As shown in FIG. 6, during processing, in order toprevent the left clamp body 41 and the right clamp body 42 to generateaxial staggering, a positioning bulge 117 and a positioning groove 118matched with each other are disposed between matching surfaces of theouter sides of the left clamp body 41 and the right clamp body 42. Thepositioning bulge 117 is a cylindrical pin provided with a flange and isvertically inserted, connected and fixed onto the matching surface ofthe left clamp body 41, and the positioning groove 118 is positioned onthe corresponding matching surface of the right clamp body 42. In orderthat the positioning bulge 117 can be conveniently guided into thepositioning groove 118, an insertion end of the cylindrical pin outwardsand inwards extends to form a cone surface for easy guide-in. In orderthat the pipe expansion processing can be conveniently performed underthe condition of poor light rays, an illumination lamp 25 is embeddedand fixed onto the surface of the pipe expander body 1 near the baffleplate 26.

As shown in FIG. 7, a tongue-shaped end surface baffle plate 119 isrotationally connected onto the end surface of the chuck body 4 inadjacent to the pipe expanding cone 6, a middle portion of the endsurface baffle plate 119 is sleeved on a rotating shaft of the chuckbody 4, an outer side end of the end surface baffle plate 119 is hookedbetween the left and right force application handles 44, and the widthis the minimum distance formed between the two force application handles44. During installation and clamping, the end surface of the pipe to beprocessed 3 is in butt joint with the side surface of the end surfacebaffle plate 119 so as to limit the axial position of the pipe to beprocessed 3.

As shown in FIG. 11 and FIG. 12, the end surface baffle plate 119 isrotationally sleeved on a pin sleeve 216, the other end of the pinsleeve 216 outwards extends along the outer end surface of the endsurface baffle plate 119 to form an end surface baffle ring 2161, theend surface baffle ring 2161 is integrally formed with the pin sleeve216, the end surface baffle ring 2161 is positioned in a groove formedin an edge of an installing hole of the end surface baffle plate 119,additionally, an outer end surface of the end surface baffle ring 2161is flushed with an outer side surface of the end surface baffle plate119, a threaded connecting component 217 is inserted and connected in amiddle hole of the pin sleeve 216 in a mutual matching manner, thethreaded connecting component 217 in the present embodiment is a flatscrew, and the threaded connecting component 217 passes through themiddle hole of the pin sleeve 216, and is then coaxially screwed in themiddle hole in the end portion of the rotating shaft, so that the endsurface baffle plate 119 is clamped between the end surface baffle ring2161 and the end surface of the chuck body 4. After the pipe to beprocessed 3 is unclamped, in order that the left handle and the righthandle of the chuck body 4 can be automatically reset, a chuck bodyreset torsional spring 218 is sleeved on the pin sleeve 216corresponding to the outer side end of the end surface baffle plate 119,and two ends of the chuck body reset torsional spring 218 arerespectively clamped in slotted grooves at the inner sides of the leftand right handles of the chuck body 4. In order to ensure that the pinsleeve 216 cannot rotate relative to the rotating shaft when thethreaded connecting component 217 is tightly screwed, and two bafflering positioning holes for positioning are formed in the end surface ofthe end surface baffle ring 2161.

During use, the chuck body is in a closed state in a free state, one endof the force application handle of the chuck body is pinched by fingersto open for a certain angle, the pipe to be processed is placed in theposition, the fingers are released after the end surface of the pipe tobe processed is flushed with the end surface baffle plate at the outerside of the inner side end surface of the chuck body (a hole opening forclamping the pipe to be processed is in a cone shape), and the chuckbody restores the closed state under the effect of a spring, and clampsthe pipe to be processed. The linkage wrench is outwards pulled to anopen state, then the chuck body clamping the pipe to be processed is putinto the pipe expanding cavity of the pipe expander, and the linkagewrench is inwards pulled to a locked state. The adjusting screw isrotated, so that the press plate tightly presses the chuck body with alittle interference, the press plate generates slight elasticdeformation, the chuck body is tightly pressed by the elasticdeformation force (when the pipe expanding processing is performedagain, the adjusting screw does not need to be adjusted again, and theadjustment is performed after working for a period of time and under thecondition that components of the mechanism are abraded). A startingswitch on the pipe expander body is pressed down for pipe expandingprocessing, and the motor stops after shaping is completed. Then, thelinkage wrench is pulled to an open state by gentle force, the chuckbody is taken out, the force application handles of the chuck body arepinched by the fingers so that the clamping end of the force applicationhandles opens for a certain angle, the pipe to be processed which hasbeen processed is taken out, and the pipe expanding processing iscompleted.

In order to realize the intelligent processing of pipe expansion, anelectronic control system is further disposed on the pipe expander. Whenthe starting switch is switched on, the electronic control system candetect the position of the linkage wrench, and when the linkage wrenchis in a locking position, the electronic control system can give out aninstruction to control the motor to be started. In the working process,if detecting that the linkage wrench is open, the electronic controlsystem can give out an instruction to make the motor drive the worm gearand worm mechanism to return the initial position before starting. Inthe pipe expanding process, with the gradual shaping of an expanded pipesocket, the output torque of the motor can be gradually increased, whena preset torque value is reached, the electronic control system cancontrol the motor to reversely rotate, and when the mandrel and thetransmission screw nut move to preset positions, a correspondingposition switch is triggered, and the electronic control system givesout an instruction to make the motor stop working. If a user starts thestarting switch under the condition of not placing the chuck body andperforms adjustment control through a mandrel extending stroke controldetection circuit, the detection circuit is respectively connected tothe mandrel bearing and the guide screw rod, the worm gear and themandrel are both made of insulation materials, and the detection circuitis a normally off circuit. When the mandrel continuously movesleftwards, the detection circuit is switched on at the moment that theflat keys are in contact with the support ring, the electronic controlsystem gives out a motor reverse rotation instrument to control themandrel to rightwards move, and the motor stops working until a positionswitch is triggered.

A chuck body detection switch can also be disposed at the side surfaceof the chuck body, and the chuck body detection switch is in a normallyon state. When the chuck body is placed and locked, the detection switchswitches on the detection circuit, the linkage wrench is in a lockedstate, and at this moment, the motor can be started to perform pipeexpanding work by pressing down the starting switch.

An intelligent control circuit for an electric pipe expander accordingto the present invention, as shown in FIG. 13, includes a single chipmicrocomputer unit 1, a mandrel stroke detection unit 2, a wrenchposition detection unit 3, a motor driving unit 4, a motor currentacquisition unit 5, a motor short circuit protection unit 6, a batteryvoltage detection unit 7, a battery temperature detection unit 8, abattery level indicating unit 9, a motor work indicating lamp 10, anillumination lamp 11 and a power supply unit 12 for providing workvoltage for the whole intelligent control circuit for the electric pipeexpander. The mandrel stroke detection unit, the wrench positiondetection unit, the motor driving unit, the motor current acquisitionunit, the motor short circuit protection unit, the battery voltagedetection unit, the battery temperature detection unit, the batterylevel indicating unit, the motor work indicating lamp and theillumination lamp are respectively connected to the single chipmicrocomputer unit, and the motor driving unit is connected to a motorfor controlling a pipe expanding head to advance/retreat.

A specific structure of the control circuit of the present embodiment isdescribed below. In the present embodiment, electric power of the powersupply unit is supplied by a battery 13. The power supply unit includesa power supply conversion circuit and a main power supply switchcircuit. As shown in FIG. 4, the power supply conversion circuitincludes a three-terminal voltage regulator module U3, thethree-terminal voltage regulator module U3 uses a 7533-2 chip, a pin 1of the three-terminal voltage regulator module U3 is connected to avoltage 7.2 V, and additionally, the pin 1 of the three-terminal voltageregulator module U3 is grounded PGND through a parallel circuit of acapacitor C13 and a capacitor C14, a pin 2 of the three-terminal voltageregulator module U3 is grounded PGND, a pin 3 of the three-terminalvoltage regulator module U3 outputs a voltage 3.3 V, and additionally,the pin 3 of the three-terminal voltage regulator module U3 is groundedDGND through a parallel circuit of a capacitor C15 and a capacitor C16.The pin 2 of the three-terminal voltage regulator module U3 is groundedDGND through a magnetic bead FB4. One path of the voltage 3.3 V outputby the pin 3 of the three-terminal voltage regulator module U3 outputs avoltage 3.3V_A through a magnetic bead FB1, and the other path of thevoltage 3.3 V output by the pin 3 of the three-terminal voltageregulator module U3 outputs a voltage 3.3V_D through a magnetic beadFB2. In the power supply conversion circuit, the voltage 7.2 V is thevoltage output by the battery, and that is, the voltage 7.2 V isconnected to a positive electrode of the battery. The power supplyconversion circuit coverts the voltage output by the battery into avoltage 3.3V_D and a voltage 3.3 V_A for each circuit module to use.

In the present embodiment, as shown in FIG. 16, the single chipmicrocomputer unit includes a single chip microcomputer U2, and thesingle chip microcomputer U2 is an STM32F031 single chip microcomputer.A pin 1 and a pin 17 of the single chip microcomputer U2 are bothconnected to a voltage 3.3V_D, a pin 5 of the single chip microcomputerU2 is connected to a voltage 3.3V_A, a pin 32 of the single chipmicrocomputer U2 is grounded, and a pin 31 of the single chipmicrocomputer U2 is grounded through a resistor R26. The illuminationlamp is disposed on the pipe expanding device, the illumination lamp isconnected to an interface J2 in FIG. 4, a pin 1 of the interface J2 isconnected to a pin 15 of the single chip microcomputer U2 through aresistor R3, and a pin 2 of the interface J2 is grounded. As shown inFIG. 15, the main power supply switch circuit includes an illuminationswitch S1 and a wake-up switch J6, one end of the illumination switch S1is grounded, the other end of the illumination switch S1 is connected tonegative electrodes of a diode D1 and a diode D3, a positive electrodeof the diode D1 is connected to a voltage 3.3V_D through a resistor R28and is connected to a pin 30 of the single chip microcomputer U2, apositive electrode of the diode D3 is connected to a positive electrodeof a diode D4, a negative electrode of the diode D4 is connected to oneend of the wake-up switch J6 and is connected to a negative electrode ofa diode D2, the other end of the wake-up switch J6 is grounded, apositive electrode of the diode D2 is connected to a voltage 3.3V_Dthrough a resistor R29 and is connected to a pin 29 of the single chipmicrocomputer U2, the positive electrode of the diode D3 is connected toa collecting electrode of a triode Q2 through a magnetic bead FB3, anemitting electrode of the triode Q2 is grounded, a base electrode of thetriode Q2 is connected to a pin 25 of the single chip microcomputer U2through a resistor R31 and is grounded through a resistor R32, thecollecting electrode of the triode Q2 is connected to a base electrodeof a triode Q1 through a resistor R30, a resistor R27 is connectedbetween the base electrode of the triode Q1 and an emitting electrode ofthe triode Q1, the emitting electrode of the triode Q1 is connected to avoltage VCC, and a collecting electrode of the triode Q1 is connected toa battery output voltage 7.2 V.

As shown in FIG. 16, the battery voltage detection unit includes aresistor R9 and a resistor R17, one end of the resistor R9 is connectedto the battery output voltage 7.2 V, the other end of the resistor R9 isgrounded through the resistor R17, a capacitor C4 is connected inparallel onto the resistor R17, and a connecting point of the resistorR9 and the resistor R17 is connected to a pin 6 of the single chipmicrocomputer U2 through a resistor R12. The battery level indicatingunit includes four light emitting diodes arranged into a row, i.e.,light emitting diodes D11 to D14, negative electrodes of the lightemitting diodes D11 to D14 are all grounded, and positive electrodes ofthe light emitting diodes D11 to D14 are respectively connected to a pin22, a pin 21, a pin 20 and a pin 11 of the single chip microcomputer U2through a resistor R1, a resistor R2, a resistor R5 and a resistor R6.The battery temperature detection unit includes a thermistor disposed ona battery pack, one end of the thermistor is grounded, the other end ofthe thermistor outputs an NTC IN signal and is connected to a pin 10 ofan interface P1, the pin 10 of the interface P1 is connected to aconnecting point of a resistor R21 and a capacitor C7, the other end ofthe resistor R21 is connected to a voltage 3.3V_D, and the other end ofthe capacitor C7 is grounded. The connecting point of the resistor R21and the capacitor C7 is connected to a pin 7 of the single chipmicrocomputer U2 through a resistor R22. A pin 1 of the interface P1 isconnected to a voltage VCC, a pin 2 of the interface P1 is connected toa battery output voltage 7.2 V, a pin 3 of the interface P1 is groundedPGND, and a pin 4, a pin 5, a pin 6 and a pin 7 of the interface P1 arerespectively connected to a pin 18, a pin 13, a pin 19 and a pin 14 ofthe single chip microcomputer U2. The interface P1 is connected to themotor driving unit through wires, the pin 4, the pin 5, the pin 6 andthe pin 7 of the interface P1 output signals to the motor driving unitso as to drive the mandrel motor of the pipe expander, the pin 7 and apin 8 of the interface P1 are connected to two ends of a currentsampling resistor disposed on the motor so as to acquire working currentof the motor and transmits the result to the motor current acquisitionunit.

As shown in FIG. 17, the motor current acquisition unit includes anoperational amplifier U1B, an inverted phase input end and an in-phaseinput end of the operational amplifier U1B are respectively connected toa pin 9 and the pin 8 of the interface P1 through a resistor R13 and aresistor R18, the inverted phase input end of the operational amplifierU1B is connected to an output end of the operational amplifier U1Bthrough a resistor R8, the in-phase input end of the operationalamplifier U1B is grounded through a capacitor C6 and is connected to avoltage 3.3V_A through a resistor R20, the output end of the operationalamplifier U1B is grounded through a series circuit of a resistor R15 anda capacitor C5, and a connecting point of the resistor R15 and thecapacitor C5 is connected to a pin 8 of the single chip microcomputerU2. As shown in FIG. 18, the motor short circuit protection unitincludes an operational amplifier U1A, an inverted phase input end ofthe operational amplifier U1A is connected to the pin 8 of the interfaceP1 through a resistor R10, the in-phase input end of the operationalamplifier U1A is connected to a voltage 3.3V_A through a resistor R16and is grounded through a resistor R19, one path of an output end of theoperational amplifier U1A is connected to a voltage 3.3V_A through aresistor R11, and the other path of the output end of the operationalamplifier U1A is connected to a pin 12 of the single chip microcomputerU2 through a resistor R14. The operational amplifier U1A and theoperational amplifier U1B use LMV358 operational amplifier chips.

As shown in FIG. 16, the motor work indicating lamp is a light emittingdiode D15, a positive electrode of the light emitting diode D15 isconnected to a pin 16 of the single chip microcomputer U2 through aresistor R7, and a negative electrode of the light emitting diode D15 isgrounded. The mandrel stroke detection unit includes a pipe expandinghead advancing position limiting switch J3 and a pipe expanding headretreating position detection switch J5 which are disposed in the pipeexpander and are respectively positioned at a front end and a rear endof the mandrel advancing and retreating stroke. Specifically, the pipeexpanding head advancing position limiting switch J3 is disposed at afront portion of the pipe expander, and corresponds to the position ofthe side surface of the chuck. The pipe expanding head retreatingposition detection switch J5 is disposed at a rear portion of the pipeexpending head and near a rear cover of the pipe expander, i.e., a pipeexpanding head retreating position detection switch 31. One pin of thepipe expanding head advancing position limiting switch J3 is grounded,the other pin of the pipe expanding head advancing position limitingswitch J3 is connected to a pin 26 of the single chip microcomputer U2through a resistor R23. One pin of the pipe expanding head retreatingposition detection switch J5 is grounded, and the other pin of the pipeexpanding head retreating position detection switch J5 is connected to apin 27 of the single chip microcomputer U2 through a resistor R25. Thewrench position detection unit includes a wrench position detectionswitch J4 disposed on the pipe expander, the arrangement position of thewrench position detection switch J4 corresponds to the position of thewrench, one pin of the wrench position detection switch J4 is grounded,and the other pin of the wrench position detection switch J4 isconnected to a pin 28 of the single chip microcomputer U2 through aresistor R24. In the present embodiment, grounding terminals all referto grounded DGND unless otherwise specified.

The motor current acquisition unit detects the motor work current, andtransmits the result to the single chip microcomputer. When a set valueis exceeded, the single chip microcomputer can control the motor to stoprotating, and the machine is prevented from burnt damage. The motorshort circuit protection unit detects whether the motor generates ashort circuit or not, once the short circuit is detected, the singlechip microcomputer immediately controls the motor to stop rotating, anda protection effect is achieved on the motor and the pipe expander. Themotor work indicating lamp, i.e., the light emitting diode D15 indicatesthe operation of the motor. The light emitting diode D15 is on when themotor rotates, and the light emitting diode D15 is off when the motorstops rotating. The battery voltage detection unit detects the batterylevel, and transmits the result to the single chip microcomputer, thesingle chip microcomputer outputs a signal to control the on-off stateof the battery level indicating lamp consisting of the four lightemitting diodes, and the battery level is indicated by the number ofon/off light emitting diodes of the four light emitting diodes arrangedinto a row. The battery temperature detection unit detects thetemperature of the battery pack, and transmits the result to the singlechip microcomputer, when the temperature exceeds a set value, the singlechip microcomputer controls the motor to stop rotating, and anovertemperature protection effect is achieved. In the pipe expandingprocess, the torque of the motor is transmitted to the single chipmicrocomputer through the interface P1, the output torque of the motorcan be gradually increased, and when the output torque reaches a setvalue, the pipe socket of an expanded copper pipe can reach a qualifieddimension. When detecting that the motor torque value reaches a presetvalue, the single chip microcomputer gives out an instruction, the motorstarts to reversely rotate until the mandrel retreats to the initialposition before starting. The pipe expanding head advancing positionlimiting switch J3 detects whether the pipe expanding head advances toexceed an allowable range or not (if YES, damage of the pipe expandermay be caused), and the pipe expanding head retreating positiondetection switch J5 detects whether the pipe expending head retreats tothe initial position before starting. The wrench position detectionswitch J4 detects whether the wrench on the pipe expander is in a closedlocked state or an open state, detection signals of the above threeswitches are respectively sent to the single chip microcomputer, thesingle chip microcomputer gives a corresponding control signal to themotor driving unit according to the detected conditions to control themotor to positively rotate, reversely rotate or stop rotating, and theautomatic control of the pipe expanding head is achieved.

The work process of each of the switches will be illuminated hereafter.

Illumination switch S1. The illumination switch S1 controls the on-offstate of the illumination lamp connected onto the interface J2. Theillumination lamp is switched on by clicking the illumination switch S1once, and is switched off after a next click. Cyclic control can beachieved. The illumination lamp is configured to illuminate a peripheralenvironment when the pipe expander is used and to enable an operator tobe able to do pipe expanding work in a dark environment.

Wake-up switch J6. The whole control circuit can be woke up by pressingand holding the wake-up switch J6 for 1.5S, after the control circuit iswoke up, if the wrench position detection switch J4 is in an on state,the result shows that the wrench is closed and locked, and the pipeexpander starts to work by pressing the wake-up switch J6 again.

Wrench position detection switch J4. When the wrench is in a closedlocking position, the wrench position detection switch J4 is switchedon, and the pipe expander is started to work by pressing down thewake-up switch J6. When the mandrel motor positively rotates, if thewrench is open, the wrench position detection switch J4 is switched off,and the motor immediately rotates reversely, so that the pipe expandinghead retreats to the initial position before starting.

Pipe expanding head retreating position detection switch J5. When themotor positively rotates, and the pipe expanding head advances to work,the pipe expanding head retreating position detection switch J5 is in anoff state. When the work of the pipe expanding head is completed, themotor reversely rotates, the pipe expanding head retreats to the initialposition before starting, the pipe expanding head retreating positiondetection switch J5 is in an on state, and at this moment, the singlechip microcomputer gives out a signal to control the motor to stopworking. The single chip microcomputer determines whether the pipeexpanding head returns to the initial position or not by detectingwhether the pipe expanding head retreating position detection switch J5is switched on or not, if the pipe expanding head retreating positiondetection switch J5 is in the on state, the result shows that the pipeexpanding head has returned to the initial position, and the motor stopsrotating.

Pipe expanding head advancing position limiting switch J3. The pipeexpanding head advancing position limiting switch J3 is in a normallyoff state, when the pipe expanding head advances to exceed the allowablerange (damage of the pipe expander may be caused), the pipe expandinghead advancing position limiting switch J3 is switched on, and at thismoment, the single chip microcomputer immediately gives out a signal tocontrol the motor to reversely rotate, so that the pipe expanding headretreats till returning to the initial position before starting. Theeffect is to avoid the occurrence of a machine damage phenomenon causedwhen an operator starts the pipe expander by mistake when the chuck isnot installed.

Embodiment 2

As shown in FIG. 9 and FIG. 10, a pressing end of the clampingconnecting rod mechanism 18 is in butt joint with a side wall of arotating shaft far away from the chuck body 4, and maintains slidingconnection with a side wall surface of the chuck body 4. The rest partsare completely the same as those of Embodiment 1.

The specific embodiments described herein are merely illustrative of theconcept of the present invention. Those skilled in the art to which thepresent invention pertains may make various modifications or additionsor similar replacements to the described specific embodiments withoutdeparting from the spirit of the present invention or beyond the scopedefined by the appended claims.

1. An electric pipe expander, comprising a pipe expander body and amandrel sliding cavity disposed on the pipe expander body, wherein achuck body capable of clamping a pipe to be processed is disposed at anopening end of the mandrel sliding cavity, a mandrel is slidablyconnected in the mandrel sliding cavity, an outer side end of themandrel is provided with an obliquely disposed pipe expanding cone, aninner side end of the mandrel is provided with an elastic bodyaccommodating cavity, a guide screw rod provided with a transmissionscrew nut is disposed on the pipe expander body opposite to an openingof the elastic body accommodating cavity, the guide screw rod extendsinto the elastic body accommodating cavity, flat keys are disposed onthe mandrel, outer side ends of the flat keys are slidably connected toa worm gear and worm mechanism in an axial direction, inner side ends ofthe flat keys are slidably connected into axial key slots of thetransmission screw nut, and an elastic body is clamped and disposedbetween the flat keys and a bottom surface of the elastic bodyaccommodating cavity.
 2. The electric pipe expander according to claim1, wherein a cone positioning hole is formed in an end surface of themandrel corresponding to the pipe expanding cone, an included angle isformed between an axial line of the cone positioning hole and an axialline of the mandrel, and the pipe expanding cone is rotationallyconnected into the cone positioning hole through a cone bearing.
 3. Theelectric pipe expander according to claim 1, wherein a mandrel bearingis embedded in the pipe expander body corresponding to the outer sideend of the mandrel, a support ring is disposed between a middle hole ofthe mandrel bearing and an outer ring surface of the mandrel, and aninner end of the support ring extends into a middle hole of a worm gearon the worm gear and worm mechanism and is in close fit with the wormgear.
 4. The electric pipe expander according to claim 1, wherein theelastic body is an annular rubber component, and the guide screw rod (8)extends into a middle hole of the elastic body.
 5. The electric pipeexpander according to claim 1, wherein a pipe expanding cavity is formedin the pipe expander body corresponding to the chuck body, a clampingend of the chuck body extends into the pipe expanding cavity and isclamped and fixed through a clamping connecting rod mechanism, and anouter end surface of the chuck body is in butt joint with acorresponding inner wall surface of the pipe expanding cavity.
 6. Theelectric pipe expander according to claim 5, wherein a connecting rodaccommodating cavity is formed in the pipe expander body correspondingto a periphery of the pipe expanding cavity, the clamping connecting rodmechanism is disposed in the connecting rod accommodating cavity, apress plate corresponding to one end of the clamping connecting rodmechanism extends into the pipe expanding cavity, and the other end ofthe clamping connecting rod mechanism is connected with a linkage wrenchextending out of the pipe expander body.
 7. The electric pipe expanderaccording to claim 6, wherein an adjusting screw is screwed andconnected onto the pipe expander body, the connecting rod mechanism isdriven when the adjusting screw screws in, such that the press plate isin butt joint with a side wall of the chuck body in a tightly clampingmanner.
 8. The electric pipe expander according to claim 6, wherein anend portion of the press plate corresponding to the chuck bodyhorizontally and outwards extends to form a trapezoidal press head, atrapezoidal clamping opening is formed in a side wall of the chuck bodycorresponding to the trapezoidal press head, and when the press platetightly clamps the chuck body, the press plate is in butt joint with abottom surface of the trapezoidal clamping opening through a bottom edgeof the trapezoidal press head, and is in butt joint with a bevel edge ata lower part of the trapezoidal clamping opening through a bevel edge ata lower part of the trapezoidal press head.
 9. The electric pipeexpander according to claim 6, wherein a horizontal position limitingpost is disposed on the pipe expanding cavity opposite to the pressplate on the clamping connecting rod mechanism, and a mutually matchedhorizontal through groove is formed in a side wall of the chuck bodycorresponding to the horizontal position limiting post.
 10. The electricpipe expander according to claim 5, wherein a pressing end of theclamping connecting rod mechanism is in butt joint with a side wall of arotating shaft far away from the chuck body, and maintains slidingconnection with a side wall surface of the chuck body.
 11. The electricpipe expander according to claim 1, wherein a plastic casing covers anoutside of the pipe expander body, the plastic casing extends outwardsto form a motor accommodating cavity, a motor is disposed in the motoraccommodating cavity, an output shaft end of the motor is connected withthe worm gear and worm mechanism, and the other end of the motor iselectrically connected with a rechargeable battery.
 12. The electricpipe expander according to claim 11, wherein the rechargeable batterycomprises a battery pack disposed in a battery pack accommodating cavityon the pipe expander body, an identity (ID) detection port, a voltagedetection port and a temperature detection port are disposed on aprotective case of the battery pack, and the ID detection port, thevoltage detection port and the temperature detection port are allconnected to a battery cell in the protective case through a batterycircuit board.
 13. The electric pipe expander according to claim 1,wherein the chuck body comprises a left clamp body and a right clampbody, middle portions of the left clamp body and the right clamp bodyare rotationally connected onto a rotating shaft, the corresponding leftclamp body and right clamp body at one side of the rotating shaft form aclamping end for clamping the pipe to be processed, and thecorresponding left clamp body and right clamp body at the other side ofthe rotating shaft respectively form force application handles.
 14. Achuck structure, adapted for the pipe expander according to claim 13,wherein a positioning bulge and a positioning groove matched with eachother are disposed between matching surfaces of the left clamp body andthe right clamp body.
 15. The chuck structure for the pipe expanderaccording to claim 14, wherein an end surface baffle plate isrotationally connected onto an end surface of the chuck body in adjacentto the pipe expanding cone, and an end surface of the pipe to beprocessed is in butt joint with a corresponding outer side surface of aninner side end of the end surface baffle plate.
 16. The chuck structurefor the pipe expander according to claim 15, wherein the end surfacebaffle plate is movably sleeved on a pin sleeve, the pin sleeve isscrewed, connected and fixed to an end portion of the rotating shaft ofthe chuck body through a threaded connecting component in close fit, anouter ring surface of the pin sleeve outwards extends along an outer endsurface of the end surface baffle plate to form an end surface bafflering (2161), and the end surface baffle plate is movably clamped betweenthe end surface baffle ring (2161) and the end surface of the chuckbody.
 17. The chuck structure for the pipe expander according to claim16, wherein the pin sleeve extends into an installing hole of the chuckbody, and a chuck body reset torsional spring is sleeved outside thecorresponding pin sleeve in the installing hole.
 18. A control circuitfor an electric pipe expander, the control circuit comprising a singlechip microcomputer unit, a mandrel stroke detection unit, a wrenchposition detection unit, a motor driving unit and a power supply unitfor providing work voltage for the whole control circuit for theelectric pipe expander, wherein the mandrel stroke detection unit, thewrench position detection unit and the motor driving unit arerespectively connected to the single chip microcomputer unit.
 19. Thecontrol circuit for the electric pipe expander according to claim 18,wherein the mandrel stroke detection unit comprises a pipe expandinghead advancing position limiting switch and a pipe expanding headretreating position detection switch, one pin of the pipe expanding headadvancing position limiting switch is grounded, the other pin of thepipe expanding head advancing position limiting switch is connected tothe single chip microcomputer unit through a resistor R23, one pin ofthe pipe expanding head retreating position detection switch isgrounded, and the other pin of the pipe expanding head retreatingposition detection switch is connected to the single chip microcomputerunit through a resistor R25.
 20. The control circuit for the electricpipe expander according to claim 18, wherein the wrench positiondetection unit comprises a wrench position detection switch, one pin ofthe wrench position detection switch is grounded, and the other pin ofthe wrench position detection switch is connected to the single chipmicrocomputer unit through a resistor R24.
 21. The intelligent controlcircuit for the electric pipe expander according to claim 20, comprisinga motor current acquisition unit, wherein the motor current acquisitionunit comprises a first operational amplifier, an inverted phase inputend and an in-phase input end of the first operational amplifier arerespectively connected to two ends of a current sampling resistordisposed in the motor driving unit through a resistor R13 and a resistorR18, the inverted phase input end of the first operational amplifier isconnected to an output end of the first operational amplifier through aresistor R8, the in-phase input end of the first operational amplifieris grounded through a capacitor C6 and is connected to a voltage 3.3V_Athrough a resistor R20, the output end of the first operationalamplifier is grounded through a series circuit of a resistor R15 and acapacitor C5, and a connecting point of the resistor R15 and thecapacitor C5 is connected to the single chip microcomputer unit.
 22. Thecontrol circuit for the electric pipe expander according to claim 21,comprising a motor short circuit protection unit, wherein the motorshort circuit protection unit comprises a second operational amplifier,an inverted phase input end of the second operational amplifier isconnected to the motor driving unit through a resistor R10, an in-phaseinput end of the second operational amplifier is connected to thevoltage 3.3V_A through a resistor R16 and is grounded through a resistorR19, one path of an output end of the second operational amplifier isconnected to the voltage 3.3V_A through a resistor R11, and the otherpath of the output end of the second operational amplifier is connectedto the single chip microcomputer unit through a resistor R14.
 23. Thecontrol circuit for the electric pipe expander according to claim 20,wherein electric power of the power supply unit is supplied by abattery, the control circuit for the electric pipe expander comprises abattery voltage detection unit and a battery level indicating unit, thebattery voltage detection unit comprises a resistor R9 and a resistorR17, one end of the resistor R9 is connected to a positive electrode ofthe battery, the other end of the resistor R9 is grounded through theresistor R17, a capacitor C4 is connected in parallel onto the resistorR17, a connecting point of the resistor R9 and the resistor R17 isconnected to the single chip microcomputer unit through a resistor R12,the battery level indicating unit comprises first, second, third andfourth light emitting diodes D11 to DH arranged into a row, negativeelectrodes of the first, second, third and fourth light emitting diodesD11 to DH are all grounded, and positive electrodes of the first,second, third and fourth light emitting diodes D1 to D111 arerespectively connected to the single chip microcomputer unit through aresistor R1, a resistor R2, a resistor R5 and a resistor R6.
 24. Theintelligent control circuit for the electric pipe expander according toclaim 23, characterized by comprising a battery temperature detectionunit, wherein the battery temperature detection unit comprises athermistor disposed on the battery, one end of the thermistor isgrounded, the other end of the thermistor is connected to a voltage3.3V_D through a resistor R21, and a connecting point of the thermistorand the resistor R21 is connected to the single chip microcomputer unitthrough a resistor R22.
 25. The intelligent control circuit for theelectric pipe expander according to claim 20, wherein the power supplyunit comprises a power supply conversion circuit and a main power supplyswitch circuit, the main power supply switch circuit comprises anillumination switch and a wake-up switch, one end of the illuminationswitch is grounded, the other end of the illumination switch isconnected to negative electrodes of a diode D1 and a diode D3, apositive electrode of the diode D1 is connected to a voltage 3.3V_Dthrough a resistor R28 and is connected to the single chip microcomputerunit, a positive electrode of the diode D3 is connected to a positiveelectrode of a diode D4, a negative electrode of the diode D4 isconnected to one end of the wake-up switch and is connected to anegative electrode of a diode D2, the other end of the wake-up switch isgrounded, a positive electrode of the diode D2 is connected to a voltage3.3V_D through a resistor R29 and is connected to the single chipmicrocomputer unit, the positive electrode of the diode D3 is connectedto a collecting electrode of a triode Q2 through a magnetic bead, anemitting electrode of the triode Q2 is grounded, a base electrode of thetriode Q2 is connected to the single chip microcomputer unit through aresistor R31 and is grounded through a resistor R32, the collectingelectrode of the triode Q2 is connected to a base electrode of a triodeQ1 through a resistor R30, a resistor R27 is connected between the baseelectrode of the triode Q1 and an emitting electrode of the triode Q1,the emitting electrode of the triode Q1 is connected to a voltage VCC, acollecting electrode of the triode Q1 is connected to a voltage 7.2 V,an illumination lamp is disposed on the pipe expander, a positiveelectrode of the illumination lamp is connected to the single chipmicrocomputer unit through a resistor R3, and a negative electrode ofthe illumination lamp is grounded.
 26. The control circuit for theelectric pipe expander according to claim 20, comprising a fifth lightemitting diode as a motor work indicating lamp, wherein a positiveelectrode of the fifth light emitting diode is connected to the singlechip microcomputer unit through a resistor R7, and a negative electrodeof the fifth light emitting diode is grounded.
 27. The control circuitfor the electric pipe expander according to claim 19, comprising a motorcurrent acquisition unit, wherein the motor current acquisition unitcomprises a first operational amplifier, an inverted phase input end andan in-phase input end of the first operational amplifier arerespectively connected to two ends of a current sampling resistordisposed in the motor driving unit through a resistor R13 and a resistorR18, the inverted phase input end of the first operational amplifier isconnected to an output end of the first operational amplifier through aresistor R8, the in-phase input end of the first operational amplifieris grounded through a capacitor C6 and is connected to a voltage 3.3 V_Athrough a resistor R20, the output end of the first operationalamplifier is grounded through a series circuit of a resistor R15 and acapacitor C5, and a connecting point of the resistor R15 and thecapacitor C5 is connected to the single chip microcomputer unit.
 28. Thecontrol circuit for the electric pipe expander according to claim 27,wherein the motor short circuit protection unit comprises a secondoperational amplifier, an inverted phase input end of the secondoperational amplifier is connected to the motor driving unit through aresistor R10, an in-phase input end of the second operational amplifieris connected to the voltage 3.3V_A through a resistor R16 and isgrounded through a resistor R19, one path of an output end of the secondoperational amplifier is connected to the voltage 3.3V_A through aresistor R11, and the other path of the output end of the secondoperational amplifier is connected to the single chip microcomputer unitthrough a resistor R14.
 29. The control circuit for the electric pipeexpander according to claim 18, comprising a motor current acquisitionunit, wherein the motor current acquisition unit comprises a firstoperational amplifier, an inverted phase input end and an in-phase inputend of the first operational amplifier are respectively connected to twoends of a current sampling resistor disposed in the motor driving unitthrough a resistor R13 and a resistor R18, the inverted phase input endof the first operational amplifier is connected to an output end of thefirst operational amplifier through a resistor R8, the in-phase inputend of the first operational amplifier is grounded through a capacitorC6 and is connected to a voltage 3.3 V_A through a resistor R20, theoutput end of the first operational amplifier is grounded through aseries circuit of a resistor R15 and a capacitor C5, and a connectingpoint of the resistor R15 and the capacitor C5 is connected to thesingle chip microcomputer unit.
 30. The control circuit for the electricpipe expander according to claim 29, wherein the motor short circuitprotection unit comprises a second operational amplifier, an invertedphase input end of the second operational amplifier is connected to themotor driving unit through a resistor R10, an in-phase input end of thesecond operational amplifier is connected to the voltage 3.3V_A througha resistor R16 and is grounded through a resistor R19, one path of anoutput end of the second operational amplifier is connected to thevoltage 3.3V_A through a resistor R11, and the other path of the outputend of the second operational amplifier is connected to the single chipmicrocomputer unit through a resistor R14.
 31. The control circuit forthe electric pipe expander according to claim 19, wherein electric powerof the power supply unit is supplied by a battery, the control circuitfor the electric pipe expander comprises a battery voltage detectionunit and a battery level indicating unit, the battery voltage detectionunit comprises a resistor R9 and a resistor R17, one end of the resistorR9 is connected to a positive electrode of the battery, the other end ofthe resistor R9 is grounded through the resistor R17, a capacitor C4 isconnected in parallel onto the resistor R17, a connecting point of theresistor R9 and the resistor R17 is connected to the single chipmicrocomputer unit through a resistor R12, the battery level indicatingunit comprises first, second, third and fourth light emitting diodesarranged into a row, negative electrodes of the first, second, third andfourth light emitting diodes are all grounded, and positive electrodesof the first, second, third and fourth light emitting diodes arerespectively connected to the single chip microcomputer unit through aresistor R1, a resistor R2, a resistor R5 and a resistor R6.
 32. Thecontrol circuit for the electric pipe expander according to claim 31,comprising a battery temperature detection unit, wherein the batterytemperature detection unit comprises a thermistor disposed on thebattery, one end of the thermistor is grounded, the other end of thethermistor is connected to a voltage 3.3V_D through a resistor R21, anda connecting point of the thermistor and the resistor R21 is connectedto the single chip microcomputer unit through a resistor R22.
 33. Thecontrol circuit for the electric pipe expander according to claim 18,wherein electric power of the power supply unit is supplied by abattery, the control circuit for the electric pipe expander comprises abattery voltage detection unit and a battery level indicating unit, thebattery voltage detection unit comprises a resistor R9 and a resistorR17, one end of the resistor R9 is connected to a positive electrode ofthe battery, the other end of the resistor R9 is grounded through theresistor R17, a capacitor C4 is connected in parallel onto the resistorR17, a connecting point of the resistor R9 and the resistor R17 isconnected to the single chip microcomputer unit through a resistor R12,the battery level indicating unit comprises first, second, third andfourth light emitting diodes arranged into a row, negative electrodes ofthe first, second, third and fourth light emitting diodes are allgrounded, and positive electrodes of the first, second, third and fourthlight emitting diodes are respectively connected to the single chipmicrocomputer unit through a resistor R1, a resistor R2, a resistor R5and a resistor R6.
 34. The control circuit for the electric pipeexpander according to claim 33, comprising a battery temperaturedetection unit, wherein the battery temperature detection unit comprisesa thermistor disposed on the battery, one end of the thermistor isgrounded, the other end of the thermistor is connected to a voltage3.3V_D through a resistor R21, and a connecting point of the thermistorand the resistor R21 is connected to the single chip microcomputer unitthrough a resistor R22.
 35. The control circuit for the electric pipeexpander according to claim 19, wherein the power supply unit comprisesa power supply conversion circuit and a main power supply switchcircuit, the main power supply switch circuit comprises an illuminationswitch and a wake-up switch, one end of the illumination switch isgrounded, the other end of the illumination switch is connected tonegative electrodes of a diode D1 and a diode D3, a positive electrodeof the diode D1 is connected to a voltage 3.3V_D through a resistor R28and is connected to the single chip microcomputer unit, a positiveelectrode of the diode D3 is connected to a positive electrode of adiode D4, a negative electrode of the diode D4 is connected to one endof the wake-up switch and is connected to a negative electrode of adiode D2, the other end of the wake-up switch is grounded, a positiveelectrode of the diode D2 is connected to a voltage 3.3V_D through aresistor R29 and is connected to the single chip microcomputer unit, thepositive electrode of the diode D3 is connected to a collectingelectrode of a triode Q2 through a magnetic bead, an emitting electrodeof the triode Q2 is grounded, a base electrode of the triode Q2 isconnected to the single chip microcomputer unit through a resistor R31and is grounded through a resistor R32, the collecting electrode of thetriode Q2 is connected to a base electrode of a triode Q1 through aresistor R30, a resistor R27 is connected between the base electrode ofthe triode Q1 and an emitting electrode of the triode Q1, the emittingelectrode of the triode Q1 is connected to a voltage VCC, a collectingelectrode of the triode Q1 is connected to a voltage 7.2 V, anillumination lamp is disposed on the pipe expander, a positive electrodeof the illumination lamp is connected to the single chip microcomputerunit through a resistor R3, and a negative electrode of the illuminationlamp is grounded.
 36. The control circuit for the electric pipe expanderaccording to claim 18, wherein the power supply unit comprises a powersupply conversion circuit and a main power supply switch circuit, themain power supply switch circuit comprises an illumination switch and awake-up switch, one end of the illumination switch is grounded, theother end of the illumination switch is connected to negative electrodesof a diode D1 and a diode D3, a positive electrode of the diode D1 isconnected to a voltage 3.3V_D through a resistor R28 and is connected tothe single chip microcomputer unit, a positive electrode of the diode D3is connected to a positive electrode of a diode D4, a negative electrodeof the diode D4 is connected to one end of the wake-up switch and isconnected to a negative electrode of a diode D2, the other end of thewake-up switch is grounded, a positive electrode of the diode D2 isconnected to a voltage 3.3V_D through a resistor R29 and is connected tothe single chip microcomputer unit, the positive electrode of the diodeD3 is connected to a collecting electrode of a triode Q2 through amagnetic bead, an emitting electrode of the triode Q2 is grounded, abase electrode of the triode Q2 is connected to the single chipmicrocomputer unit through a resistor R31 and is grounded through aresistor R32, the collecting electrode of the triode Q2 is connected toa base electrode of a triode Q1 through a resistor R30, a resistor R27is connected between the base electrode of the triode Q1 and an emittingelectrode of the triode Q1, the emitting electrode of the triode Q1 isconnected to a voltage VCC, a collecting electrode of the triode Q1 isconnected to a voltage 7.2 V, an illumination lamp is disposed on thepipe expander, a positive electrode of the illumination lamp isconnected to the single chip microcomputer unit through a resistor R3,and a negative electrode of the illumination lamp is grounded.
 37. Thecontrol circuit for the electric pipe expander according to claim 19,comprising a fifth light emitting diode as a motor work indicating lamp,wherein a positive electrode of the fifth light emitting diode isconnected to the single chip microcomputer unit through a resistor R7,and a negative electrode of the fifth light emitting diode is grounded.38. The control circuit for the electric pipe expander according toclaim 18, comprising a fifth light emitting diode as a motor workindicating lamp, wherein a positive electrode of the fifth lightemitting diode is connected to the single chip microcomputer unitthrough a resistor R7, and a negative electrode of the fifth lightemitting diode is grounded.